Noise - no problem for SMOS

SMOS payload ready for acoustic testing

27 March 2007

The SMOS payload flight model has just passed another of the many milestones on the road to launch, with the successful completion of the important acoustic test at ESA's test facilities in the Netherlands.

The payload flight model arrived at ESA-ESTEC just over two weeks ago to be put though an intensive period of testing. During the programme, which is still on-going, the payload was subjected to a simulation of the massive vibration and noise levels it will eventually have to endure during launch.

The exercise was carried out in ESA-ESTEC's Large European Acoustic Facility, which is a large chamber equipped with huge trumpet-like horn structures that emit nitrogen and generate extremely high levels of noise. In order to cover the whole spectrum, such as would be generated by the launcher, there are quite a number of these horns in the chamber - each covering a specific acoustic range.

Electrical and critical alignment points were compared before and after the procedure to ensure that the tests hadn't caused and shifts and that no damage had been sustained. In addition, runs with low-level noise were performed before and after the test proper, where the acoustic response of the accelerometers mounted all over the payload gave very precise information as to whether anything mechanical had changed as a result of the violent test environment.

The good new is that the SMOS payload survived it all – without out any damage what so ever - and is now ready to face its next ordeal, which will be the thermal balance and thermal vacuum test. We will keep you posted!